This invention relates broadly to a process of preparing arylsulfonium salts and more particularly to producing bis-(diphenylsulfoniophenyl)-sulfide bis-chloride (which for convenience will hereinafter be referred to as "bis") in higher yield and purity than has previously been possible.
Procedures for producing triaryl sulfonium salts are described in the relevant art. For example, U.S. Pat. No. 2,807,648 to Pitt describes reacting benzene or a halogenated benzene with aluminum chloride then reacting sulfur mono- or di-chloride then adding chlorine to produce a triaryl sulfonium chloride/aluminum trichloride complex.
This method produces mixtures of triarylsulfonium chlorides containing low to moderate proportions of "bis"--which is present in the reaction mixture which makes the isolation of the desired "bis" product difficult due to the physical and chemical similarity of the products. Alternative procedures using arylsulfides are undesirable due to the poor yields of the salt and relatively high expense.
The present invention overcomes the problems and disadvantages of the aforementioned methods by producing "bis" with improved yields and purity.
It is thus the primary object of the present invention to prepare mixtures of triaryl sulfonium chlorides with a higher content of "bis" than has been produced by other methods. Indeed, using the procedures of the invention purities in excess of 80% and approaching theoretical can be obtained. Using similar procedures other arylsulfonium halides can be produced economically and in good yields which arylsulfonium halides have not previously been readily available.
Additional objects and advantages of the invention will be set forth and will be apparent from the following detailed description of the invention.